ENVE road handlebars use a proprietary 2-piece bar end plug.
Here is the installation video.
To install you will need:
- Needle nose pliers
- Remove the bar tape
- Use the needle nose pliers to pull the retention plug from the bar end
- Remove the plug
- Insert the new plug
- Insert the new retention plug- gently tap with pliers to get it to seat
- Flip the edges of the plug away from the bar
- Re-wrap bar, and flip the edges down around the bar to finish